Commit fe4955a

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atcoder-live

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BIT

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	`1`	`+// Binary Indexed Tree (Fenwick Tree)`
	`2`	`+// https://youtu.be/lyHk98daDJo?t=7960`
	`3`	`+template<typename T>`
	`4`	`+struct BIT {`
	`5`	`+ int n;`
	`6`	`+ vector<T> d;`
	`7`	`+ BIT(int n=0):n(n),d(n+1) {}`
	`8`	`+ void add(int i, T x=1) {`
	`9`	`+ for (i++; i <= n; i += i&-i) {`
	`10`	`+ d[i] += x;`
	`11`	`+ }`
	`12`	`+ }`
	`13`	`+ T sum(int i) {`
	`14`	`+ T x = 0;`
	`15`	`+ for (i++; i; i -= i&-i) {`
	`16`	`+ x += d[i];`
	`17`	`+ }`
	`18`	`+ return x;`
	`19`	`+ }`
	`20`	`+};`

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