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https://github.com/halfrost/LeetCode-Go.git
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32 lines
817 B
Go
32 lines
817 B
Go
package leetcode
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type NumMatrix struct {
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cumsum [][]int
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}
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func Constructor(matrix [][]int) NumMatrix {
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if len(matrix) == 0 {
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return NumMatrix{nil}
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}
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cumsum := make([][]int, len(matrix)+1)
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cumsum[0] = make([]int, len(matrix[0])+1)
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for i := range matrix {
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cumsum[i+1] = make([]int, len(matrix[i])+1)
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for j := range matrix[i] {
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cumsum[i+1][j+1] = matrix[i][j] + cumsum[i][j+1] + cumsum[i+1][j] - cumsum[i][j]
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}
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}
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return NumMatrix{cumsum}
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}
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func (this *NumMatrix) SumRegion(row1 int, col1 int, row2 int, col2 int) int {
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cumsum := this.cumsum
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return cumsum[row2+1][col2+1] - cumsum[row1][col2+1] - cumsum[row2+1][col1] + cumsum[row1][col1]
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}
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/**
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* Your NumMatrix object will be instantiated and called as such:
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* obj := Constructor(matrix);
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* param_1 := obj.SumRegion(row1,col1,row2,col2);
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*/
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