HDU #1166. 敌兵布阵

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题意

线段树，单点修改，区间查询

题解

略

调试记录

cmd判断错误

#include <cstdio>
#include <cstring>
#define maxn 50005

using namespace std;

struct Tree{
	struct node{
		int l, r, key, lazy;
	}a[maxn << 2];
	int val[maxn];
	
	void clear(){
		memset(a, 0, sizeof a);
		memset(val, 0, sizeof val);
	}
	
	void Build(int cur, int l, int r){
		a[cur].l = l, a[cur].r = r;
		a[cur].lazy = 0;
		if (l == r){
			a[cur].key = val[l];
			return;
		}
		int mid = (l + r) >> 1;
		Build(cur << 1, l, mid);
		Build(cur << 1 | 1, mid + 1, r);
		a[cur].key = a[cur << 1].key + a[cur << 1 | 1].key; 
	}
	
	void pushdown(int cur){
		if (a[cur].lazy == 0) return;
		a[cur << 1].lazy += a[cur].lazy;
		a[cur << 1 | 1].lazy += a[cur].lazy;
		a[cur << 1].key += a[cur].lazy * (a[cur << 1].r - a[cur << 1].l + 1);
		a[cur << 1 | 1].key += a[cur].lazy * (a[cur << 1 | 1].r - a[cur << 1 | 1].l + 1);
		a[cur].lazy = 0;
	}
	
	void update(int cur, int l, int r, int k){
		if (a[cur].l > r || a[cur].r < l) return;
		if (a[cur].l >= l && a[cur].r <= r){
			a[cur].key += (a[cur].r - a[cur].l + 1) * k;
			a[cur].lazy += k;
			return;
		}
		update(cur << 1, l, r, k);
		update(cur << 1 | 1, l, r, k);
		a[cur].key = a[cur << 1].key + a[cur << 1 | 1].key;
	}
	
	int Query(int cur, int l, int r){
		if (a[cur].l > r || a[cur].r < l) return 0;
		if (a[cur].l >= l && a[cur].r <= r) return a[cur].key;
		pushdown(cur);
		return Query(cur << 1, l, r) + Query(cur << 1 | 1, l, r);
	}
}t;
int T, n;
int main(){
	scanf("%d", &T);
	for (int ti = 1; ti <= T; ti++){
		printf("Case %d:\n", ti);
		t.clear();
		scanf("%d", &n);
		for (int i = 1; i <= n; i++) scanf("%d", &t.val[i]);
		t.Build(1, 1, n);
		char cmd[50];
		scanf("%s", cmd);
		while (cmd[0] != 'E'){
			int x, y;
			scanf("%d%d", &x, &y);
			if (cmd[0] == 'Q') printf("%d\n", t.Query(1, x, y));
			if (cmd[0] == 'A') t.update(1, x, x, y);
			if (cmd[0] == 'S') t.update(1, x, x, -y);
			scanf("%s", cmd);
		}
	}
	return 0;
}