zoj 1610 Count the Colors(线段树)

题目链接：zoj 1610 Count the Colors

题目大意：给定一段区间，进行N次操做，每次为一段区间涂上一种颜色，最后输出每种颜色占的长度。

解题思路：线段树维护，最后在一一查询计数。

#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;

const int maxn = 8005;
#define lson(x) ((x)<<1)
#define rson(x) (((x)<<1)|1)
int lc[maxn << 2], rc[maxn << 2], s[maxn << 2];

inline void pushdown(int u) {
    if (s[u] != -1) {
        s[lson(u)] = s[rson(u)] = s[u];
        s[u] = -1;
    }
}

void build (int u, int l, int r) {
    lc[u] = l;
    rc[u] = r;
    s[u] = -1;

    if (l == r)
        return;

    int mid = (l + r) >> 1;
    build(lson(u), l, mid);
    build(rson(u), mid + 1, r);
}

void modify(int u, int l, int r, int w) {
    if (l <= lc[u] && rc[u] <= r) {
        s[u] = w;
        return;
    }

    pushdown(u);
    int mid = (lc[u] + rc[u]) >> 1;
    if (l <= mid)
        modify(lson(u), l, r, w);
    if (r > mid)
        modify(rson(u), l, r, w);
}

int query(int u, int x) {
    if (lc[u] == x && x == rc[u])
        return s[u];
    pushdown(u);
    int mid = (lc[u] + rc[u]) >> 1;
    if (x <= mid)
        return query(lson(u), x);
    else
        return query(rson(u), x);
}

int N, ans[maxn];

int main () {

    int l, r, c;
    while (scanf("%d", &N) == 1) {
        build (1, 0, 8000);
        for (int i = 0; i < N; i++) {
            scanf("%d%d%d", &l, &r, &c);
            modify(1, l, r - 1, c);
        }

        int pre = -1;
        memset(ans, 0, sizeof(ans));
        for (int i = 0; i <= 8000; i++) {
            int k = query(1, i);
            if (k != pre && k != -1)
                ans[k]++;
            pre = k;
        }

        for (int i = 0; i <= 8000; i++) {
            if (ans[i])
                printf("%d %d\n", i, ans[i]);
        }
        printf("\n");
    }
    return 0;
}