Painting some colored segments on a line, some previously painted segments may be covered by some the subsequent ones.
Your task is counting the segments of different colors you can see at last.
Input
The first line of each data set contains exactly one integer n, 1 <= n <= 8000, equal to the number of colored segments.
Each of the following n lines consists of exactly 3 nonnegative integers separated by single spaces:
x1 x2 c
x1 and x2 indicate the left endpoint and right endpoint of the segment, c indicates the color of the segment.
All the numbers are in the range [0, 8000], and they are all integers.
Input may contain several data set, process to the end of file.
Output
Each line of the output should contain a color index that can be seen from the top, following the count of the segments of this color, they should be printed according to the color index.
If some color can't be seen, you shouldn't print it.
Print a blank line after every dataset.
Sample Input
5
0 4 4
0 3 1
3 4 2
0 2 2
0 2 3
4
0 1 1
3 4 1
1 3 2
1 3 1
6
0 1 0
1 2 1
2 3 1
1 2 0
2 3 0
1 2 1
Sample Output
1 1
2 1
3 1
1 1
0 2
1 1
Painting some colored segments on a line, some previously painted segments may be covered by some the subsequent ones.
Your task is counting the segments of different colors you can see at last.
Input
The first line of each data set contains exactly one integer n, 1 <= n <= 8000, equal to the number of colored segments.
Each of the following n lines consists of exactly 3 nonnegative integers separated by single spaces:
x1 x2 c
x1 and x2 indicate the left endpoint and right endpoint of the segment, c indicates the color of the segment.
All the numbers are in the range [0, 8000], and they are all integers.
Input may contain several data set, process to the end of file.
Output
Each line of the output should contain a color index that can be seen from the top, following the count of the segments of this color, they should be printed according to the color index.
If some color can't be seen, you shouldn't print it.
Print a blank line after every dataset.
Sample Input
5
0 4 4
0 3 1
3 4 2
0 2 2
0 2 3
4
0 1 1
3 4 1
1 3 2
1 3 1
6
0 1 0
1 2 1
2 3 1
1 2 0
2 3 0
1 2 1
Sample Output
1 1
2 1
3 1
1 1
0 2
1 1
水题线段树
#include <map>
#include <set>
#include <list>
#include <queue>
#include <stack>
#include <vector>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
const int N = 8010;
int cnt[N], ret;
struct node
{
int l, r;
int col;
}tree[N << 2], seg[N], rec[N];
void build (int p, int l, int r)
{
tree[p].l = l;
tree[p].r = r;
tree[p].col = -1;
if (l == r)
{
return;
}
int mid = (l + r) >> 1;
build(p << 1, l, mid);
build(p << 1 | 1, mid + 1, r);
}
void update(int p, int l, int r, int col)
{
if (tree[p].l >= l && r >= tree[p].r)
{
tree[p].col = col;
return;
}
if (tree[p].col != -1)
{
tree[p << 1].col = tree[p].col;
tree[p << 1 | 1].col = tree[p].col;
tree[p].col = -1;
}
int mid = (tree[p].l + tree[p].r) >> 1;
if (r <= mid)
{
update(p << 1, l, r, col);
}
else if (l > mid)
{
update(p << 1 | 1, l, r, col);
}
else
{
update(p << 1, l, mid, col);
update(p << 1 | 1, mid + 1, r, col);
}
}
void query (int p)
{
if (tree[p].col != -1)
{
rec[ret].l = tree[p].l;
rec[ret].r = tree[p].r;
rec[ret++].col = tree[p].col;
return;
}
query(p << 1);
query(p << 1 | 1);
}
int main()
{
int n, l, r;
while(~scanf("%d", &n))
{
l = 10000, r = -10000;
memset (cnt, 0, sizeof(cnt));
for (int i = 0; i < n; ++i)
{
scanf("%d%d%d", &seg[i].l, &seg[i].r, &seg[i].col);
l = min(l, seg[i].l);
r = max(r, seg[i].r);
}
build(1, l + 1, r);
ret = 0;
for (int i = 0; i < n; ++i)
{
update(1, seg[i].l + 1, seg[i].r, seg[i].col);
}
query(1);
cnt[rec[0].col]++;
for (int i = 1; i < ret; ++i)
{
if (rec[i].col != rec[i - 1].col)
{
cnt[rec[i].col]++;
}
else if (rec[i].l > rec[i - 1].r + 1)
{
cnt[rec[i].col]++;
}
}
for (int i = 0; i <= 8000; ++i)
{
if (cnt[i] != 0)
{
printf("%d %d\n", i, cnt[i]);
}
}
printf("\n");
}
return 0;
}

本文介绍了一个基于线段树的数据结构算法问题,旨在解决颜色区间的覆盖与可见计数问题。通过构建线段树并更新节点状态,实现了对不同颜色可见区间的高效计算。

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