504. Base 7

//本文内容来自StarSight,欢迎访问。


Given an integer, return its base 7 string representation.

Example 1:

Input: 100
Output: "202"

Example 2:

Input: -7
Output: "-10"

Note: The input will be in range of [-1e7, 1e7].


其实就是7进制表示。

        boolean isZ =true;
        int x = 0;
        String base ="";
        int bit = 9;
        
        if(num<0)
            isZ=false;
        num = Math.abs(num);
        
        for(;bit>0;){
            if(Math.pow(7,bit)>num)
                bit--;
            else
                break;
        }
        for(int i=bit;i>=0;i--){
            x =(int)(num /Math.pow(7,i));
            num -= (int)(x*Math.pow(7,i));
            base +=x;
        
        }
        if(!isZ)
            base="-"+base;
        return base;


另一种科学实现:

来自:http://blog.youkuaiyun.com/mcf171/article/details/55003173

public class Solution {  
    public String convertTo7(int num) {  
         StringBuffer sb = new StringBuffer("");  
        if(num == 0) return "0";  
        boolean flag = num > 0 ? false : true;  
        num = Math.abs(num);  
        while(num != 0){  
            sb.insert(0,num%7);  
            num /= 7;  
        }  
        if(flag)sb.insert(0,"-");  
          
        return sb.toString();  
    }  
}  



!SESSION 2025-09-01 15:44:44.798 ----------------------------------------------- eclipse.buildId=4.6.0.I20160606-1100 java.version=10.0.1 java.vendor=Oracle Corporation BootLoader constants: OS=win32, ARCH=x86_64, WS=win32, NL=zh_CN Framework arguments: -product org.eclipse.epp.package.jee.product Command-line arguments: -os win32 -ws win32 -arch x86_64 -product org.eclipse.epp.package.jee.product !ENTRY org.eclipse.osgi 4 0 2025-09-01 15:44:58.648 !MESSAGE Application error !STACK 1 org.eclipse.e4.core.di.InjectionException: java.lang.NoClassDefFoundError: javax/annotation/PostConstruct at org.eclipse.e4.core.internal.di.InjectorImpl.internalMake(InjectorImpl.java:386) at org.eclipse.e4.core.internal.di.InjectorImpl.make(InjectorImpl.java:294) at org.eclipse.e4.core.contexts.ContextInjectionFactory.make(ContextInjectionFactory.java:162) at org.eclipse.e4.ui.internal.workbench.swt.E4Application.createDefaultHeadlessContext(E4Application.java:490) at org.eclipse.e4.ui.internal.workbench.swt.E4Application.createDefaultContext(E4Application.java:504) at org.eclipse.e4.ui.internal.workbench.swt.E4Application.createE4Workbench(E4Application.java:203) at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:626) at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:336) at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:604) at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:148) at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:138) at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:134) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:104) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:388) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:243) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.base/java.lang.reflect.Method.invoke(Unknown Source) at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:673) at org.eclipse.equinox.launcher.Main.basicRun(Main.java:610) at org.eclipse.equinox.launcher.Main.run(Main.java:1519) at org.eclipse.equinox.launcher.Main.main(Main.java:1492) Caused by: java.lang.NoClassDefFoundError: javax/annotation/PostConstruct at org.eclipse.e4.core.internal.di.InjectorImpl.inject(InjectorImpl.java:151) at org.eclipse.e4.core.internal.di.InjectorImpl.internalMake(InjectorImpl.java:375) ... 23 more Caused by: java.lang.ClassNotFoundException: javax.annotation.PostConstruct cannot be found by org.eclipse.e4.core.di_1.6.0.v20160319-0612 at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:398) at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:361) at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:353) at org.eclipse.osgi.internal.loader.ModuleClassLoader.loadClass(ModuleClassLoader.java:161) at java.base/java.lang.ClassLoader.loadClass(Unknown Source) ... 25 more !ENTRY org.eclipse.e4.ui.workbench 4 0 2025-09-01 15:44:58.665 !MESSAGE FrameworkEvent ERROR !STACK 0 java.lang.NoClassDefFoundError: javax/annotation/PreDestroy at org.eclipse.e4.core.internal.di.InjectorImpl.disposed(InjectorImpl.java:426) at org.eclipse.e4.core.internal.di.Requestor.disposed(Requestor.java:154) at org.eclipse.e4.core.internal.contexts.ContextObjectSupplier$ContextInjectionListener.update(ContextObjectSupplier.java:78) at org.eclipse.e4.core.internal.contexts.TrackableComputationExt.update(TrackableComputationExt.java:111) at org.eclipse.e4.core.internal.contexts.TrackableComputationExt.handleInvalid(TrackableComputationExt.java:74) at org.eclipse.e4.core.internal.contexts.EclipseContext.dispose(EclipseContext.java:176) at org.eclipse.e4.core.internal.contexts.osgi.EclipseContextOSGi.dispose(EclipseContextOSGi.java:106) at org.eclipse.e4.core.internal.contexts.osgi.EclipseContextOSGi.bundleChanged(EclipseContextOSGi.java:139) at org.eclipse.osgi.internal.framework.BundleContextImpl.dispatchEvent(BundleContextImpl.java:903) at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:230) at org.eclipse.osgi.framework.eventmgr.ListenerQueue.dispatchEventSynchronous(ListenerQueue.java:148) at org.eclipse.osgi.internal.framework.EquinoxEventPublisher.publishBundleEventPrivileged(EquinoxEventPublisher.java:213) at org.eclipse.osgi.internal.framework.EquinoxEventPublisher.publishBundleEvent(EquinoxEventPublisher.java:120) at org.eclipse.osgi.internal.framework.EquinoxEventPublisher.publishBundleEvent(EquinoxEventPublisher.java:112) at org.eclipse.osgi.internal.framework.EquinoxContainerAdaptor.publishModuleEvent(EquinoxContainerAdaptor.java:156) at org.eclipse.osgi.container.Module.publishEvent(Module.java:476) at org.eclipse.osgi.container.Module.doStop(Module.java:634) at org.eclipse.osgi.container.Module.stop(Module.java:498) at org.eclipse.osgi.container.SystemModule.stop(SystemModule.java:191) at org.eclipse.osgi.internal.framework.EquinoxBundle$SystemBundle$EquinoxSystemModule$1.run(EquinoxBundle.java:165) at java.base/java.lang.Thread.run(Unknown Source) Caused by: java.lang.ClassNotFoundException: javax.annotation.PreDestroy cannot be found by org.eclipse.e4.core.di_1.6.0.v20160319-0612 at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:398) at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:361) at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:353) at org.eclipse.osgi.internal.loader.ModuleClassLoader.loadClass(ModuleClassLoader.java:161) at java.base/java.lang.ClassLoader.loadClass(Unknown Source) ... 21 more !SESSION 2025-09-01 15:45:13.969 ----------------------------------------------- eclipse.buildId=4.6.0.I20160606-1100 java.version=10.0.1 java.vendor=Oracle Corporation BootLoader constants: OS=win32, ARCH=x86_64, WS=win32, NL=zh_CN Framework arguments: -product org.eclipse.epp.package.jee.product Command-line arguments: -os win32 -ws win32 -arch x86_64 -product org.eclipse.epp.package.jee.product !ENTRY org.eclipse.osgi 4 0 2025-09-01 15:45:20.390 !MESSAGE Application error !STACK 1 org.eclipse.e4.core.di.InjectionException: java.lang.NoClassDefFoundError: javax/annotation/PostConstruct at org.eclipse.e4.core.internal.di.InjectorImpl.internalMake(InjectorImpl.java:386) at org.eclipse.e4.core.internal.di.InjectorImpl.make(InjectorImpl.java:294) at org.eclipse.e4.core.contexts.ContextInjectionFactory.make(ContextInjectionFactory.java:162) at org.eclipse.e4.ui.internal.workbench.swt.E4Application.createDefaultHeadlessContext(E4Application.java:490) at org.eclipse.e4.ui.internal.workbench.swt.E4Application.createDefaultContext(E4Application.java:504) at org.eclipse.e4.ui.internal.workbench.swt.E4Application.createE4Workbench(E4Application.java:203) at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:626) at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:336) at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:604) at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:148) at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:138) at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:134) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:104) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:388) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:243) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.base/java.lang.reflect.Method.invoke(Unknown Source) at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:673) at org.eclipse.equinox.launcher.Main.basicRun(Main.java:610) at org.eclipse.equinox.launcher.Main.run(Main.java:1519) at org.eclipse.equinox.launcher.Main.main(Main.java:1492) Caused by: java.lang.NoClassDefFoundError: javax/annotation/PostConstruct at org.eclipse.e4.core.internal.di.InjectorImpl.inject(InjectorImpl.java:151) at org.eclipse.e4.core.internal.di.InjectorImpl.internalMake(InjectorImpl.java:375) ... 23 more Caused by: java.lang.ClassNotFoundException: javax.annotation.PostConstruct cannot be found by org.eclipse.e4.core.di_1.6.0.v20160319-0612 at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:398) at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:361) at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:353) at org.eclipse.osgi.internal.loader.ModuleClassLoader.loadClass(ModuleClassLoader.java:161) at java.base/java.lang.ClassLoader.loadClass(Unknown Source) ... 25 more !ENTRY org.eclipse.e4.ui.workbench 4 0 2025-09-01 15:45:20.405 !MESSAGE FrameworkEvent ERROR !STACK 0 java.lang.NoClassDefFoundError: javax/annotation/PreDestroy at org.eclipse.e4.core.internal.di.InjectorImpl.disposed(InjectorImpl.java:426) at org.eclipse.e4.core.internal.di.Requestor.disposed(Requestor.java:154) at org.eclipse.e4.core.internal.contexts.ContextObjectSupplier$ContextInjectionListener.update(ContextObjectSupplier.java:78) at org.eclipse.e4.core.internal.contexts.TrackableComputationExt.update(TrackableComputationExt.java:111) at org.eclipse.e4.core.internal.contexts.TrackableComputationExt.handleInvalid(TrackableComputationExt.java:74) at org.eclipse.e4.core.internal.contexts.EclipseContext.dispose(EclipseContext.java:176) at org.eclipse.e4.core.internal.contexts.osgi.EclipseContextOSGi.dispose(EclipseContextOSGi.java:106) at org.eclipse.e4.core.internal.contexts.osgi.EclipseContextOSGi.bundleChanged(EclipseContextOSGi.java:139) at org.eclipse.osgi.internal.framework.BundleContextImpl.dispatchEvent(BundleContextImpl.java:903) at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:230) at org.eclipse.osgi.framework.eventmgr.ListenerQueue.dispatchEventSynchronous(ListenerQueue.java:148) at org.eclipse.osgi.internal.framework.EquinoxEventPublisher.publishBundleEventPrivileged(EquinoxEventPublisher.java:213) at org.eclipse.osgi.internal.framework.EquinoxEventPublisher.publishBundleEvent(EquinoxEventPublisher.java:120) at org.eclipse.osgi.internal.framework.EquinoxEventPublisher.publishBundleEvent(EquinoxEventPublisher.java:112) at org.eclipse.osgi.internal.framework.EquinoxContainerAdaptor.publishModuleEvent(EquinoxContainerAdaptor.java:156) at org.eclipse.osgi.container.Module.publishEvent(Module.java:476) at org.eclipse.osgi.container.Module.doStop(Module.java:634) at org.eclipse.osgi.container.Module.stop(Module.java:498) at org.eclipse.osgi.container.SystemModule.stop(SystemModule.java:191) at org.eclipse.osgi.internal.framework.EquinoxBundle$SystemBundle$EquinoxSystemModule$1.run(EquinoxBundle.java:165) at java.base/java.lang.Thread.run(Unknown Source) Caused by: java.lang.ClassNotFoundException: javax.annotation.PreDestroy cannot be found by org.eclipse.e4.core.di_1.6.0.v20160319-0612 at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:398) at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:361) at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:353) at org.eclipse.osgi.internal.loader.ModuleClassLoader.loadClass(ModuleClassLoader.java:161) at java.base/java.lang.ClassLoader.loadClass(Unknown Source) ... 21 more
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